Children who have the most sedentary lifestyles appear to be at greatest risk of developing chronic fatigue syndrome, or myalgic encephalomyelitis (CFS/ME), in later life, a British study shows.

“Contrary to previous suggestions that high levels of exercise increase risk, we found that the most sedentary children were at greatest risk,” write Dr. Russell Viner, from Royal Free and University College Medical School, and Dr. Matthew Hotopf from the Institute of Psychiatry in London.

Viner and Hotopf analysed data from the 1970 British birth cohort, which included 16,567 subjects who were regularly monitored from babyhood until the age of 30.

They found that the risk of CFS/ME was significantly increased in females as opposed to males, with high social class in childhood, and with having a limiting long-standing medical condition in childhood.

Children who were sedentary at the age of 10 were about twice as likely to develop CFS/ME, the authors report in the online edition of the British Medical Journal this week, and those who played more sport in their spare time had a lower risk.

“Hours of sport played at school was not associated with risk of CFS/ME, which suggests that the protective effect of exercise lies within the individual and family rather than in time-tabled school activities.”

There was no association between risk of later CFS/ME and factors such as maternal psychological disorder, psychological problems in childhood, academic ability, allergic tendencies, birth weight, birth order or obesity.

“Our findings do not support a role for previously suggested risk factors for CFS/ME,” Viner and Hotopf write. This adds “further weight to current public health efforts to promote healthy exercise and reduce sedentary behaviour among children.”

Chief Executive of the Association of Young People with ME, Maryjane Willows, told Reuters Health: “These findings cut across previous understanding that have implicated that stressful events, high academic achievement and higher levels of exercise may have a role to play in the CFS/ME.”

She added: “Any study of this debilitating illness should be welcomed. However, these results may be explained by the use of people who self-reported CFS/ME and may not have had a clinical diagnosis.”

SOURCE: British Medical Journal Online First, October 9, 2004.